Blueprint coating



Patented Apr. 30, 194i) "UNITED STATE PATENT orrlcr.

BLUEPRINT oos'rnvG Robert Bowling Barnes, Stamford, and Garnet Phili Ham, oldGi-eenwich, Conm, assignors to American Oyanamid Company, 'NewYork, N. Y., a corporation of Maine No Drawing.

Application June 14, 1939,

Serial No. 279,056

8 Claims.

This invention relates to blueprint paper coating and more particularly to improved coating solutions for blueprint paper.

Blueprint paper and similar papers such as,

for example, Van Dyke negative paper, require coating of the paper with an aqueous solution of the sensitizing agent. Two of the important characteristics of a good blueprint coating are speed and latitude; that is to say, the exposure time which is required to give suificiently dark backgrounds for ordinary reproduction and the range of exposure through which tones of adequate color can be obtained. The attempts to 2,165,166, of July 4, 1939, in which it is. shown.

that amidine compounds when added to a blueprint coating solution have a catalytic eflect in creased as compared to the ordinary blueprint coatings.

In another copending application of Garnet Philip Ham and Robert Bowling Barnes, Serial- No. 225,904 filed August 20, 1938, it is shown that treatment of blueprint paper with certain types v of wetting agents prior to the application of the blueprint coating solution results in improved blueprint paper as compared to paper not previously coated with the wetting agent.

The blueprint paper produced by using the improved high speed formula described in U. 8. Patent No. 2,165,166, of July 4, 1939, and in connection with the method of pre-treatment of the paper with a wetting agent as described in copending application, Serial No. 225,904, is a high quality paper but there is the disadvantage of the necessity for two steps in carrying out the process as it is not feasible to mix the two before using. The fact that it is necessary to apply two individual and separate coatings, namely, the

first coating of the wetting agent and thesecond coating of the sensitized solution, increases the cost of production and somewhat increases the opportunity for lack of uniformity in the final product.

According to the present invention, we have found that sulfonic acid type wetting agents, such that the speed and latitude of the paper are inguanidine salts, instead of the sodium salts, can be used in blueprint coating solutions to produce a blueprint paper having improved speed, latitude and greater stability than, ordinary blue- 5 print coating.

In general, the class of compounds capable of producing the improved results are the amidine salts of sulfodicarboxylic acid esters as represented by the following type formula:

RlRiN p rm, Hmsm H x V in which Rum and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals, R4 is a dicarboxylic acid ester, and X is a member of the group consist- 1118 Of R1,

The substituents R1, R2 and R3 may be the same-or different in various compounds included within the scope of the invention and it should be understood that each symbol is intended to represent any member of the group defined;

An inspection of the above type formula .will' such guanyl-urea compounds as guanyl-urea itself, monoor dimethyl guanyl-urea, diphenylguanyl-urea, tetraethyl guanyl-urea, and triethanol guanyl-urea are organic bases which will form salts of sulfodicarboxylic acid esters.

The following salts are examples of those thatv r 'have been found to give excellent results: the

guanidine salt of di(methylamy1) ester of sulfosuccinic acid, thev guanidine salt of diamyl ester of sulfosuccinic acid, and the guanidine salt of dioctylsulfosuccinic acid.

The reason why these compounds give excellent results in increasing the speed and latitude of the blueprint or sensitized coating has not been definitely determined. However, we believe that there is a two-fold effect: first. the'catalytic effect of the guanidine radical promotes greater sensitivity and stability to the coating; and,

second, the radical producing the wetting eflect induces a lower surface tension in the solution which permits greater and more rapid absorption by the paper resulting in a more substantive and uniform coating. These reasons are advanced as a possible partial explanation without limiting the invention thereto.

The invention will be described in detail in conjunction with the following specific examples in which these guanidine salts are incorporated in a blueprint formulation without requiring additional components to eflect the completion.

EXAMPLI 1 SolutionA Water ml Guanidine salt of dioctylsulfosuccinic acid -1 g SolutionB Water ml Ferric ammonium oxalate g Sodium ferricyanide liquor (21.5 g./l :ml.) ..-ml Potassium citrate g 1.00 Citric acid -g.. 1.00

Solution A is prepared by heating to about 50' C. to eflect rapid dissolution and then cooled to about 25 C. and added to solution B.

A sample of ordinary 21 lb.-50% rag stock paper was coated with this sensitized solution and compared to a control paper coated with a solution of the same general formula omitting the guanidine salt of dioctylsulfosuccinic acid.

The speed and latitude of the coating were markedly superior to those of the control.

Exanrtx 2 ester.

sitised formula of Example 2 and compared to a control. The results are the same as'Example 1.

Emu: 3

Blueprint paper as described in Example 1 was coated with a sentitlzed solution prepared according to the formula of Example 1 except the guanidine salt of the di(methylamyl) ester of sulfosuccinic acid .was used instead of the guanidine salt of dioctylsulfosuccinic acid.

Exnrrnn '4 A blueprint coating was prepared asdescribed in Example 2 except the guanidine salt of the digiethylamyl) ester of sulfosuccinic acid was us The results are the same as those of Example 3.

what we claim is: v

1. A blueprint paper coated with a light sensi tive blueprint coating composition containing an amidine salt of a sulfodicarboxylic acid ester in an effective amount.

2. A light sensitive blueprint coating composition having as one of the ingredients an amidine salt of a suliodicarboxylic acid ester in an effec tive amount.

3. A blueprint paper coated with a light sensitive blueprint coating composition containing a guanidine salt of a sulfosuccinic acid ester in an eil'ective amount.

4. A light sensitive blueprint coating composition having as one' of the ingredients a guanidine salt of a sulfosuccinic acid ester in an eifective amount.

5. A blueprint paper coated with a light sensitive blueprint coating composition containing the guanidine salt of dioctylsulfosuccinic acid ester.

6. A light sensitive blueprint coating composition having as one .of the ingredients the guanidine salt of dioctylsulfosuccinic acid ester.

'7. A blueprint paper coated with a light sensitive blueprint coating composition containing the guanidine salt of di(methylamyl) sulfosuccinic acid ester.

8. A light sensitive blueprint coating composition having as one of the ingredients the guanidine salt of di(methylamyl) sulfosuccinic acid ROBERT BOWLING BARNES.

GARNET PHILIP HAM. 

